WO2022253575A1

WO2022253575A1 - Method and device for producing fertiliser granules

Info

Publication number: WO2022253575A1
Application number: PCT/EP2022/063467
Authority: WO
Inventors: Michael Jacob; Johannes Buchheim
Original assignee: Glatt Ingenieurtechnik Gesellschaft mit beschränkter Haftung
Priority date: 2021-06-01
Filing date: 2022-05-18
Publication date: 2022-12-08
Also published as: EP4347533A1; DE102021205595A1

Abstract

The invention relates to a method and to a device (1) for producing fertiliser granules (2) from a processed starting material (8) formed as a combustion residue.

Description

Method and device for the production of fertilizer granulate

The invention relates to a method and a device for producing fertilizer granules from a processed starting material formed as a combustion residue.

Agricultural use of the soil removes mineral raw materials such as phosphorus-containing compounds. These are to be fed back into the soil for further agricultural use in the form of artificial, mineral fertilizers, whereby the mineral raw materials are advantageously obtained from raw material sources that have only been used to a limited extent so far and from the point of view of sustainability.

The fertilizer granules produced all have in common that they must meet the requirements of the Fertilizer Ordinance (DüMV), in particular with regard to pollution, in particular heavy metal pollution.

Corresponding methods and devices for the production of fertilizers have long been state of the art and are briefly summarized below:

European patent application EP 3037 396 A1 discloses a method for producing a phosphate-containing fertilizer from an ash or char of a sludge from wastewater treatment or waste fermentation by a) mixing the ash or char with a mineral acid and incubating the resulting suspension in a first vessel, b) separating wet solids from the suspension and replacing the separated solids by further ash or char, mixing the further ash or char with the mineral acid remaining in the first vessel and incubating the resulting suspension in the first vessel, c) converting these solids into a second vessel and mixing the solids with a pH-neutral, basic or buffered aqueous liquid, d) separating part of the liquid produced by the mixing from the second vessel, separating heavy metal ions contained therein and returning this liquid to the second vessel, e) absence removing wet solids from the liquid contained in the second vessel; and f) repeating steps b) through f). The resulting mixture is then pelleted in the conditioning unit.

The German patent application DE 102016 116 633 A1 describes a process for the production of fertilizer granules, a suspension being produced from at least one phosphate-containing secondary raw material and at least one mineral acid, the sparingly soluble phosphates of the at least one phosphate-containing secondary raw material being at least partially dissolved in the suspension produced and /or be converted into a water- and/or neutral ammonium citrate-soluble phosphate phase and this suspension is then fed to a granulation, whereby the fertilizer granules are formed and the P2O5 content contained in the fertilizer granules is greater than 75% is soluble in neutral ammonium citrate and also consists of fertilizer granules with a spherical form factor of 0.85 or greater, with a granule size distribution in the range from 1 mm (d05) to 10 mm (d95) and a P205 content greater than 8%, the P205 Content greater than 75% neutral ammonium citrate soluble.

The international patent application WO 2019/149405 A1 shows a method for producing a granulate that improves the pedosphere, as well as the associated device and a granulate obtained via the method. The process has the process steps a) the production of a raw material dispersion comprising at least one inorganic secondary phosphate and at least one reactant, the proportion of a liquid phase in the raw material dispersion being greater than 30%, with an incubation time between inorganic secondary phosphate and reactant between 1 up to 100 minutes, b) separating part of the liquid phase of the raw material dispersion, c) granulating and/or extruding the remaining raw material dispersion with a reduced liquid phase, d) either recycling the liquid phase separated in process step b) without at least part wise heavy metal separation in process step a) for the production of a raw material dispersion or at least partial separation of heavy metals from the liquid phase separated in process step b) and discharge of these

Heavy metals from the process with subsequent recycling of the separated liquid phase low in heavy metals to produce a raw material dispersion analogous to process step a) and/or in process step c) and e) repeating process steps a) to d). The disadvantage of the methods described in the prior art is that the reaction between the starting materials in the form of combustion residues and the reactant, in addition to the pollutants in the form of heavy metals, also releases a significant proportion of phosphates from the starting materials and thus only can still be used to a limited extent for the production of fertilizer granules.

The object of the invention is therefore to provide an alternative method and an alternative device for the production of fertilizer granules, with a significantly larger part of the phosphates being made usable for the production of the fertilizer granules.

This object is achieved in a method of the type mentioned at the outset in that a first suspension is produced from the starting material and a solvent in a processing phase, as a result of which the pollutants bound in the starting material in the first suspension are at least partially dissolved out of the starting material by the solvent , in order to then at least partially separate the extract from the first suspension to obtain a raffinate, in order to heat an intermediate product based on the raffinate in the absence of air and without oxygen supply at a working pressure in a production phase that follows the preparation phase, so that under production of the fertilizer granules pyrolysis of the intermediate product takes place. Various thermo-chemical conversion processes are referred to as pyrolysis, in which compounds are split at high temperatures and in the absence of oxygen. Advantageously, in the treatment phase, when extracting the pollutants, which are formed in particular as heavy metals, by the solvent from the combustion At least the sparingly soluble phosphate bound in the starting material is not dissolved in the starting material formed in the residue and remains in it. The phosphates remaining in the raffinate can thus be introduced into the fertilizer granules to a much greater extent in the production phase that follows the processing phase. Due to the large surface of the fertilizer granules produced in the form of coal, water and nutrients are bound quickly. This prevents putrefaction processes and is therefore beneficial to animal welfare. By adding fertilizer granules in the form of charcoal, valuable nutrients are immediately bound in the charcoal and can therefore no longer be washed out.

During the pyrolysis, the intermediate product is heated to a temperature of 150°C to 1500°C, in particular to a temperature of between 400°C and 1200°C. The high temperatures break the bonds within the molecules and the exclusion of oxygen prevents combustion, with the aim of producing solid secondary energy carriers. The working pressure is also advantageously in the form of atmospheric air pressure plus or minus 100 mbar. Atmospheric air pressure is caused by the weight of the air envelope that surrounds the earth up to a height of about 500 km. In addition, the atmospheric air pressure is subject to weather-related fluctuations. At sea level, the average atmospheric pressure is 1013.25 mbar. By varying the working pressure, there is the possibility of influencing the parameters of the pyrolysis and thus carrying out the pyrolysis at lower temperatures if necessary. According to an embodiment of the method that is advantageous in this respect, the extract that is at least partially separated from the first suspension in the preparation phase is regenerated in a regeneration step and recirculated to produce the first suspension. This significantly reduces solvent consumption, making the process for manufacturing fertilizer granules more efficient and cost-effective. The regeneration of the extract preferably takes place by means of ion selection and/or precipitation and/or extraction and/or a step comprising evaporation/distillation and/or electrochemical purification. The precipitation is particularly preferably carried out as a sulfide precipitation using thiosulfate salts. The sulphide precipitation by using thiosulphate salts has the advantage that the formation of sulfur gases, which can only be cleaned again with a great deal of equipment, is prevented. More preferably, the pollutants, in particular the heavy metals, are separated by electrochemical purification, for example by means of a pair of platinum-graphite electrodes. The processing phase is expediently repeated once or several times with a starting material formed as a raffinate. Such a processing cascade results in a more complete extraction of the pollutants, in particular the heavy metals, from the starting material, so that the concentration of pollutants in the raffinate decreases with each processing phase. Different solvents are preferably used in different processing phases. Due to the different solvents, it is possible to extract the various pollutants which are bound in the starting material to different extents, since the bound pollutants are dissolved out of the starting material with different degrees of goodness by different solvents and adsorbed in the solvent according to their own properties. According to an additional advantageous embodiment of the process, additives are added to the first suspension and/or the raffinate and/or the intermediate product. In particular, phosphorus, sulfur and nitrogen are considered to be additives. The additives are added in the amount required for the fertilizer granules to be produced and in any combination of additives during the process, but expediently during the production of the first suspension and/or during the production of the second suspension. However, the additives are preferably added during the preparation of the second suspension as an intermediate product.

To enrich it with phosphorus, the first and/or the second suspension can be supplemented with phosphorus sources such as apatite, hydroxyapatite, monocalcium phosphate (MCP), diammonium phosphate (DAP), dicalcium phosphate (DCP), tricalcium phosphate (TCP) or monoammonium phosphate (MAP) or potassium dihydrogen phosphate in any amount or combination are supplied. An enrichment with phosphorus can also be achieved by digesting the raffinate, also referred to as suspension residue, in the second suspension with phosphoric acid.

An enrichment with sulfur can expediently be carried out by digesting the raffinate with sulfuric acid in the second suspension, i. H. in the manufacturing phase. In addition, the addition of, for example, alkali or

Alkaline earth sulfates to the first and / or second suspension achieved an enrichment with elemental sulfur and / or an ammonium sulfate solution.

An enrichment of the fertilizer granules with nitrogen is achieved in that the raffinate in the production phase is mixed with nitric acid, preferably when preparing the second suspension. In addition, urea and/or ammonium sulfate can be added to the first and/or second suspension to enrich it with nitrogen. The advantage of ammonium sulphate is that the nitrogen is present as NH4 ⁺ , which leads to better plant availability and/or plant nutrition. The sulfur present in the ammonium sulphate is also better absorbed by the plants as sulphate. For the production of NPK fertilizer granules, the addition of various of the aforementioned additives is necessary, expediently in particular nitric acid, urea, DCP and/or potassium salts such as potassium nitrate, potassium chloride or potassium dihydrogen phosphate. In the production phase before the pyrolysis, a second suspension of raffinate and reactant is produced as an intermediate product in a preferred development of the process. By leaching the raffinate, the sparingly soluble phosphates, which are still contained in the raffinate after extraction, are separated from it and converted into phosphates that are more easily utilized by plants.

The reactant is advantageously an acid or an alkali, with the acid expediently being a mineral and/or organic acid or any mixture of these. The three strong, inorganic acids hydrochloric acid, sulfuric acid and nitric acid, but also phosphoric acid and carbonic acid are referred to as mineral acids. Organic acids are organic chemical compounds that have at least one functional group that enters into an equilibrium reaction with water or other protonatable solvents, in particular for example carboxylic acids. In this regard, the organic acid is a short-chain carboxylic acid containing up to six carbon atoms, such as formic acid, acetic acid, citric acid, glycolic acid, diglycolic acid, and mixtures thereof. In addition, the organic acid preferably has a carbon-to-oxygen ratio of 1:1 or 1:2.

According to an additional advantageous development, the starting material is ground in a grinding step before and/or the first suspension is ground during the preparation phase. More preferably, the intermediate product based on the raffinate is ground in a grinding step before and/or during the production phase. The grinding process that takes place before the granulation increases the process stability, in that the starting materials and/or the first suspension and/or the raffinate and/or the second suspension are comminuted by the grinding process. As a result, the reaction participation of the starting materials and/or the first suspension and/or the intermediate product is also increased by increasing the surface area of the starting materials of the first suspension and/or the intermediate product, i. H. the reaction kinetics are increased, which accelerates the reaction between the corresponding reacti onspartnern, which in turn leads to more uniform conversion of the starting materials of the first suspension and/or that of the intermediate product and thus also to time savings. At the same time, the risk of clogging at bottlenecks in the device, especially in nozzles of the granulation devices, on flaps and slides or the like, is reduced. In addition, any sedimentation that occurs as a result of the grinding process is minimized.

It is also advantageous that the starting material can also be crushed in a grinding unit during the processing phase or can be comminuted, e.g. in a recirculation device having a grinding unit for the first suspension. The raffinate can also be ground during the production of the second suspension, expediently in a recirculation device having a grinding unit for the second suspension.

It is also advantageous if the reactant at the start of the reaction, i. H., when the reactants are mixed to form the second suspension, has a temperature of 10 °C to 40 °C. Expediently, the organic acids do not decompose at these temperatures. In addition, at temperatures of the reactant of 10° C. to 40° C., less sparingly soluble high-temperature phases of the phosphate are formed during the reaction with the raffinate. Furthermore, the reactant is advantageously initially introduced and the intermediate product based on the raffinate is added to it.

According to a preferred embodiment of the method, the first suspension has an extraction time of in particular up to 90 minutes and/or the second suspension has a reaction time of up to 90 minutes, preferably between 20 minutes and 60 minutes. The extraction time is the period during which the solvent is in contact with the starting material in order to extract the pollutants, in particular heavy metals, from the starting material into the solvent. The first suspension preferably has an extraction time of, in particular, up to 90 minutes. However, significantly longer extraction times of days and weeks may also be necessary. In appropriate cases, the first suspension is then intermediately stored in containers designed as buffer stores. Response time is the period of time in which the raffinate is in contact with the reactant in order to break down the raffinate, also referred to as suspension residue, and in particular to convert the poorly soluble phosphates into phosphates that are easier for plants to utilize. Surprisingly, it has been found that the aforementioned extraction and reaction times, preferably in any combination, contribute to the production of fertilizer granules that are easier for plants to utilize.

According to a further development, the temperature of the second suspension is between 20.degree. C. and 80.degree. C. during the reaction time. It was found that these temperatures are particularly advantageous for the production of the second suspension and the reaction between the raffinate and the reactant which takes place in the process, in order to extract the sparingly soluble phosphates from the raffinate.

Expediently, the first suspension and/or the intermediate product is supplied with mechanical energy to break up agglomerates, in particular by means of ultrasound. The supply of mechanical energy serves to improve homogenization of the first product and/or the intermediate product, in particular to break up agglomerates, and thus to support the breakdown of the raffinate in the production phase and thereby also to reduce the reaction time. Expediently, high-pressure homogenization devices, plate vibrators or sonotrodes or the like are used to introduce mechanical energy. The homogenization leads to a reduction in viscosity and thus an increase in flowability.

In a preferred embodiment, the second suspension has a solids content of 30% to 70%, in particular others from 40% to 65%. Surprisingly, it has been found that a solids content of 30% to 70% in the second suspension is optimal for the granulation that follows the production of the second suspension, particularly with regard to spray granulation or spray agglomeration, and therefore very uniform fertilizer granules with a narrow particle size distribution he can be generated.

The granulation of the second suspension is preferably carried out by means of spray granulation or spray agglomeration. This is expediently carried out in particular in a fluidization apparatus designed as a high-temperature fluidized bed apparatus or high-temperature spouted bed apparatus. Advantageously, this produces the fertilizer granules whose properties, such as particle size, moisture content, etc., can be set or are set in a targeted manner. In an embodiment of the process that is advantageous in this regard, the intermediate product formed as the second suspension is granulated by means of spray granulation or spray agglomeration. Advantageously, the process for producing fertilizer granules is a continuous process. The advantages of continuous processes include consistent product quality, a production quantity of fertilizer granules that can be determined over the period of time, less manual handling of the fertilizer granules, improved work safety, fewer personnel requirements, less cleaning of the device and lower production costs for the fertilizer granules. However, a discontinuous or semi-continuous process is also conceivable. In addition, the object is achieved in a device of the type mentioned in that the device a processing unit with an extraction stage, which has a container for producing a first suspension from the starting material and a solvent, and with a separating device for at least partially separating the extract from the first suspension to obtain a raffinate and that the device further has a production unit which has a pyrolysis device for producing the fertilizer granules from an intermediate product based on the raffinate. The device is advantageously suitable for carrying out the above-described, preferred method for producing fertilizer granules batchwise, semi-continuously or continuously and thus producing corresponding fertilizer granules which have very low levels of pollutants, preferably in the form of heavy metals . Surprisingly, as a result of the treatment phase carried out in the treatment unit, the phosphates remain improved in the raffinate and can be completely converted into the fertilizer granules in the production phase that follows the treatment phase. Various thermo-chemical conversion processes are referred to as pyrolysis, in which compounds are cleaved at high temperatures and in the absence of oxygen. Due to the large surface of the fertilizer granules produced in the form of coal, water and nutrients are quickly bound. This prevents putrefaction processes and is therefore beneficial to animal welfare. By adding fertilizer granules in the form of charcoal, valuable nutrients are immediately bound in the charcoal and can therefore no longer be washed out.

Any pollutants contained in the raffinate, such as dioxins, are also converted to coal by the pyrolysis. The coal takes on the task of a soil improvement substrate by binding nutrients and in particular it serves to fix CO. In addition, the formation of humus is stimulated, etc. .

In a preferred development of the device, the production unit has a leaching device, the leaching device having a container for producing a second suspension from the raffinate and the reactant. By leaching the raffinate, the sparingly soluble phosphates, which are still contained in the raffinate after extraction, are separated from it and converted into phosphates that are easier for plants to use.

In this regard, the container for preparing the first suspension and the container for preparing the second suspension are designed as separate containers. This device is expediently very well suited for carrying out the continuous process for the production of fertilizer granules.

Alternatively, in this regard, the container for producing the first suspension and the container for producing the second suspension are designed as one container. Such a term design of the device for the production of fertilizer medium granules causes savings in investment costs and a lower space requirement.

According to an additional advantageous embodiment of the device, the pyrolysis device is designed as a granulation device in the form of a fluidization device, in particular as a high-temperature fluidized-bed device or the high-temperature spouted-bed device. This advantageously produces the fertilizer granules whose properties, such as grain size, moisture content, etc., are targeted adjustable. Here, the second suspension is in particular continuously granulated. The high temperatures in the pyrolysis device break the bonds within the molecules and the exclusion of oxygen prevents combustion with the aim of producing solid secondary energy carriers.

The processing unit expediently has several containers for producing a suspension and one or more separating devices for at least partially separating the extract from the corresponding suspension, with the plurality of containers being assigned one separating device or each container being assigned a separate separating device. Advantageously, extract and raffinate are separated from one another by the separating device, with the extract being at least partially separated off, so that the raffinate can be further processed with higher quality, namely with lower pollution.

According to a further preferred development of the device, the processing unit has one or more regeneration devices for the extract. This is advantageous because the extract can be regenerated and thus reused. In this regard, the treatment unit has one or more recirculation devices for the regenerated solvent. This reduces solvent consumption and makes the process significantly more efficient and cost-effective. The extract is preferably regenerated by means of ion selection or precipitation or extraction or a step comprising evaporation/distillation or electrochemical treatment, for example by means of a pair of platinum-graphite electrodes. The precipitation is particularly preferably carried out as a sulfide precipitation using thiosulfate salts. The sulfide precipitation using thiosulfate salts has the advantage that the formation of sulfur gases, which can only be cleaned again with a very large amount of equipment, is prevented.

In addition, in a corresponding further development, the production unit has a pH value control device. This is preferably arranged in the production unit upstream of the granulator. By controlling the pH value using a pH value control device, it is possible to set the pH value of the second suspension formed from raffinate and reactant precisely and, for example, to check it after the reaction but before the granulation. Adjusting the pH of the second suspension has an effect on the stickiness of the second suspension, which in turn is of very great importance for the atomization of the second suspension using the granulator, which is preferably designed as a fluidization apparatus. The more acidic the suspension, the stickier it is. The pH value is preferably measured in the second suspension and the pH value is adjusted via the pH value control device. The pH value control can also be designed as an additional, external control loop.

According to an additional preferred embodiment of the device, the leaching device, in particular the container for producing the second suspension, is designed as a tubular reactor. The design as a tubular reactor has the advantage that this design can be implemented easily and inexpensively. In addition, the tubular reactor has the advantage that a higher conversion and higher selectivity can be achieved compared to a stirred tank reactor. The tubular reactor thus combines the advantages of the batch reactor (discontinuous stirred tank reactor) and the continuous stirred tank reactor. The invention is explained in more detail with reference to the accompanying undersigned voltage and show in this

1 shows a first embodiment of the device for producing fertilizer granules, FIG. 2 shows a second embodiment of the device for producing fertilizer granules,

FIG. 3 shows a third embodiment of the device for the production of fertilizer granules,

FIG. 4 shows a fourth embodiment of the device for producing fertilizer granules,

Figure 5 shows a fifth embodiment of the device for the production of fertilizer granules and

FIG. 6 shows a sixth embodiment of the device for producing fertilizer granules. Unless otherwise specified, the following description relates to all of the embodiments illustrated in the drawing of a preferred device 1 and the corresponding method for producing fertilizer granules 2. The method for producing fertilizer granules 2 is preferably designed as a continuous method .

The device 1 has a preparation unit 3 and a production unit 4 . The processing unit 3 is described in more detail below: The processing unit 3 has an extraction stage 11 having a container 5 for producing a first suspension 6 from a starting material 8 in the form of a combustion residue containing pollutants 7 and a solvent 9, as well as a separating device 10.

Combustion residues are referred to as starting material 8 containing pollutants 7, in particular from the mono- or co-incineration of sewage sludge and/or animal excretions and/or animal meal and/or animal remains and/or animal carcasses and/or liquid manure and/or fermentation residues and /or wood and/or bone meal both as a single substance or as a mixture thereof.

Liquid compounds are referred to as solvents 9, which can dissolve solid, liquid and gaseous substances without chemically changing them or themselves. During a release process, the lattice energy of the connection is eliminated. In the process, molecules or ions of a compound that are less firmly bound in terms of energy are released by the solvent 9, trapped in the form of a shell and stabilized. Likewise, the internal forces of the solvent molecules must be overcome. The energy required is obtained from the attraction between the dissolved pollutants 7 and the solvent 9. In the case of water this process is called hydration, in other solvents 9 solvation. In addition to water, which is characterized by its ability to form three-dimensional hydrogen bonds, many inorganic and organic liquids are used as solvents 9 . They belong to the non-aqueous systems and are divided into the categories protic, aprotic non-polar and aprotic polar according to their ability to release protons or other ions and their polarity. In addition, any mixture of different solvents 9 is also referred to as solvent 9 . The container 5 has a starting material inlet 12, a solvent inlet 13 and a container outlet 14. Furthermore, the container 5 can comprise a heat transfer device 15 which is suitable for supplying or removing heat from the container 5 containing the first suspension 6 and thus for controlling the temperature of the container 5 . Accordingly, the container 5 is expediently designed as a double-walled container 16 . In the container 5, after the addition of the starting material 8 containing the pollutant 7 and the solvent 9, during a period referred to as the extraction time, the pollutants 7, in particular the heavy metals, are removed by the solvent 9 from the starting material 8 of the first suspension 6 dissolved out, whereby the pollutants 7 off in the starting material 8 and accumulate in the solvent 9. Other pollutants 7 can also be extracted from the starting material 8 by the solvent 9 . The enrichment of the solvent 9 takes place until the maximum loading of the solvent 9 is reached. The first suspension 6 preferably has an extraction time of, in particular, up to 90 minutes. However, significantly longer extraction times of days and weeks can also be necessary, depending on the starting material 8 and solvent 9 used. In appropriate cases, the first suspension 6 is then temporarily stored in containers (not shown) designed as buffer storage. In order to achieve the fastest and most complete removal of the pollutants 7, in particular heavy metals, from the starting material 8, the solvent 9 must be provided with large exchange surfaces and short diffusion paths, ie the extraction kinetics are accelerated. This can be achieved by crushing the starting material 8 containing the pollutants 7 by means of a grinding device 17 assigned to the processing unit 3, whereby also increases process stability. The optimized extraction kinetics lead to time savings and thus to a shorter extraction time. At the same time, the risk of clogging at bottlenecks in the device 1, in particular at valves, flaps and slides or the like, is reduced.

The grinding device 17 can be arranged in front of and/or on the container 5 for the production of the first suspension 6 . The starting materials 8 for producing the first suspension 6 are comminuted in the grinding device 17 so that they have an average particle diameter of preferably less than or equal to 5 mth. If the grinding process--also referred to as the grinding step--is carried out before the production of the first suspension 6 before (upstream) the container 5, this takes place as dry grinding of the starting materials 8, as shown in FIG. In contrast to this, the starting materials 8 are wet-milled during the production of the first suspension 6 in the container 5 . Such wet grinding with subsequent return of the first suspension 6 to the container 5 is shown, for example, in FIG. 3 . With a combination of dry and wet grinding in the process, the grinding process takes place both before (upstream) in the container 5 and during the production of the first suspension 6 in the container 5, shown for example in FIG. 4. By using the different grinding processes When designing the process, the plant constructor has the opportunity to respond to the different starting materials and always optimally adapt the process to them and to respond to the specifications, such as the investment costs, of the operator. Dry grinding has the advantage of high grinding efficiency with little space requirement and low specific energy consumption. In the Dry grinding is the desired final fineness of the starting materials 8 freely and precisely adjustable. With wet grinding, even coarse starting materials can be processed with a low specific energy consumption. In addition, the agitator bearing does not come into contact with the product. A combination of dry and wet grinding enables post-grinding of the starting materials 8 and the first suspension 6. The advantages here are a significantly reduced total energy consumption, an increase in throughput with the same product fineness or alternatively an increase in product fineness with the same throughput. Furthermore, the combination of dry and wet grinding makes it possible to use continuously and discontinuously operating grinding devices 17, such as, for example, mills. In the simplest form of leaching, the starting material 8 and the solvent 9 are mixed well with one another. For this purpose, a mixing device 18 is expediently arranged in the container 5, shown in Fig. 1, among other things. The extract 19 with the pollutants 7 now dissolved therein is then at least partially separated from the raffinate 20 within a separating device 10 assigned to the extraction stage 11, the Separator 10 has an extract and a raffinate outlet and a separator outlet. Separators, filter devices such as, in particular, filter presses, centrifuges or the like are expediently used as the separating device 10 . In the embodiment shown in FIG. 3, the container 5 and separator 10 are constructed as a structural unit.

Expediently, the first suspension 6 is supplied with mechanical energy for breaking up agglomerates, in particular by means of ultrasound. The supply of mechanical energy follows by means of homogenizing device 21 and is used for better homogenization of the first suspension 6, in particular the breaking up of agglomerates and thus also for reducing the extraction time, as well as reducing the viscosity and thus increasing the flowability. For this purpose, the processing unit 3 has a homogenizing device 21 suitable for introducing mechanical energy, in particular in the form of a plate vibrator or a sonotrode, which is arranged on the container 5 . Furthermore, the treatment unit 3 has a regeneration device 22 with an extract inlet and a regeneration device outlet, as shown in FIG. 3, for example. The regeneration carried out in the regeneration device 22--also referred to as a regeneration step--of the extract 19 is usually carried out by evaporation/distillation and/or by electrochemical treatment of the extract using a pair of platinum-graphite electrodes. During evaporation/distillation, the solvent 9 is evaporated and a concentrated extract solution 23 containing the pollutants 7 remains. The solvent 9 is then condensed and can be reused. The extract solution 23 can also be fed to further processing/treatment for heavy metal recovery.

The processing unit 3 has a recirculation device 24 for this purpose, as shown in FIG. 4, for example. The recirculation device 24 is suitable for recirculating the solvent 9 regenerated from the extract 19 into the container 5 of an extraction stage 11 . Such a recirculation reduces the solvent consumption originally required considerably, since the supply of the regenerated solvent 9 means that less fresh solvent 9 has to be supplied. The processing unit 3 can also - as shown, for example, in Fig. 5 and 6, have any number of extraction stages 11 that form a processing cascade 25 the. 5 shows an embodiment with two extraction stages 11 and FIG. 6 shows an embodiment with three extraction stages 11. To make it easier to distinguish between the same objects, these are identified below with the reference symbols ',''' etc., e.g the extraction stage 11', 11'', 11'''. A treatment cascade 25 can have any number of extraction stages 11, for example 2, 3, 4, . . . n. Each extraction stage 11 forms its own treatment phase.

In FIG. 5, each container 5 is assigned a separating device 10 for at least partially separating the extract 19 from the corresponding first suspension 6, a regeneration device 22 for regenerating the corresponding extract 19 and a recirculation device 24 for recirculating the regenerated solvent 9. In the embodiment of the device 1 described in FIG. 5, different solvents 9, namely solvents 9' and solvents 9'', are used in the different extraction stages 11.

In contrast to this, in FIG. 6 the containers 5 for the production of a first suspension 6 are each assigned a separating device 10, the extracts 19 being regenerated via a collecting device in the shared regeneration device 22 and the regenerated solvent 9 via a shared recirculation device 24 is recirculated. A common solvent 9 is used in the device of FIG. Here, the processing phase is repeated twice with a starting material 8 formed as a raffinate 20 . The raffinate 20 is then supplied as an intermediate product 26 from the processing unit 3 to the production unit 4 . The raffinate 20 in this case is the part of the first suspension 6 that remains after the partial separation of the extract 20 from the first suspension 6 as a so-called suspension residue. Manufacturing unit 4 is described in more detail below:

The production unit 4 has a pyrolysis device 27. This has a pyrolysis device inlet designed as an inlet and a pyrolysis device outlet designed as an outlet. The pyrolysis device 27 is preferably designed as a rotary kiln, as a pyrolysis furnace or as a granulation device and is suitable for heating the intermediate product 26 based on the raffinate 20 in the absence of air and without oxygen supply at a working pressure, so that pyrolysis of the intermediate product 26 takes place while the fertilizer granules 2 are produced . For this purpose, the intermediate product 26 based on the raffinate 20 can be adjusted/changed before it enters the pyrolysis device 27 by adding additional substances. The pyrolysis device 26 is particularly preferably designed as a granulation device in the form of a fluidization apparatus, in particular as a high-temperature fluidized bed apparatus or high-temperature spouted bed apparatus, so that the intermediate product 26 designed as the second suspension 28 is granulated by means of spray granulation or spray agglomeration. For example, in FIG. 1 the pyrolysis device 27 is designed as a pyrolysis furnace, in FIGS. 2 and 4 as a high-temperature fluidized bed apparatus and in FIGS. 3 and 5 as a high-temperature spouted bed apparatus, with FIG. 6 showing a rotary kiln.

The method is preferably carried out in such a way that the second suspension 28 is continuously granulated. The intermediate product 26 is expediently heated to a temperature of 150° C. to 1,500° C., in particular to a temperature between 400° C. and 1,200° C., during the pyrolysis taking place in the pyrolysis device 27 . The working pressure during pyrolysis is atmospheric air pressure + 100 mbar.

Furthermore, the production unit 4 has a leaching device 29, which has a container 30 for the production of a second suspension 28 from raffinate 20 and a reactant 31, as shown in Fig. 2, among other things. The container 30 has an intermediate product inlet 32 , also referred to as a raffinate inlet, a reactant inlet 33 and a tank outlet 34 . Furthermore, the container 30 can comprise a heat transfer device 15 which is suitable for supplying or removing heat from the second suspension 28 and thus for controlling the temperature of the container 30 . The container 30 is accordingly suitably designed as a jacketed container 16 . A corresponding embodiment is shown in FIG. 2, for example. In a further preferred embodiment, the reactant 31 is placed in the container 30 and the raffinate 20 is added to it. More preferably, the reactant 31 has a temperature of 10° C. to 40° C. when it is added via the reactant feed 33 . The second suspension 28 expediently has a solids content of 30% to 70%, in particular 40% to 65%.

The leaching device 29, in particular the container 30 for producing the second suspension 28, is preferably designed as a tubular reactor 35. An embodiment of the leaching unit 29 as a tubular reactor 35 is shown in FIG. 4, for example. The reactant 31 breaks down the raffinate 20 in the container 30 by reacting the raffinate 20 with the reactant 31 during a period referred to as the reaction time, so that the sparingly soluble phosphates are converted into phosphates that are easier for plants to utilize. The reaction time between raffinate 20 and reactant 31, in particular the acid, is expediently up to 90 minutes second suspension 28 in container 30 preferably has a temperature between 20° C. and 80° C. during the reaction time. The heat transfer device 15 is ge suitable for adjusting the temperature of the second suspension 28 in the container 30 accordingly.

The container 5 for producing the first suspension 6 and the container 30 for producing the second suspension 28 can be designed as separate containers 5, 30, as shown by way of example in FIG. In contrast to this, it is also possible, as realized in an embodiment that is not shown, for the container 5 for producing the first suspension 6 and the container 30 for producing the second suspension 28 to be designed as one container 5, 30.

An acid or a base is referred to as the reactant 31, the acid expediently being a mineral and/or an organic acid or any mixture of these. Short-chain carboxylic acids having up to six carbon atoms are preferably used as the organic acid, such as formic, acetic, citric, glycolic, diglycolic acid. More preferably, the organic acid has a carbon-to-oxygen ratio of 1:1 or 1:2. The temperature of the reactant 31 at the Addition in the range of 10 °C to 40 °C reduces in particular the degeneration of the reactants 31.

Additives 36 can be supplied to the first suspension 6 and/or the second suspension 28, with additives 36 being in particular phosphorus, sulfur and nitrogen. For example, water, dried sewage sludge or lignin sulfonate are also used as additive 36 . The additives 36 are added in the quantity required for the fertilizer granules 2 to be produced and in any combination of the additives 36 via an additive feed 37. However, the additives 36 are preferably added during the production of the second suspension 28 in the container 30.

To enrich it with phosphorus, the first and/or the second suspension 6, 28 can use phosphorus sources such as apatite, hydroxyapatite, monocalcium phosphate (MCP), dicalcium phosphate (DCP), dicalcium phosphate (DCP), tricalcium phosphate (TCP) or monoammonium phosphate (MAP) or Potassium dihydrogen phosphate is added in any quantity or combination. An enrichment with phosphorus can also be achieved by digesting the raffinate 20, also referred to as suspension residue, which is also referred to as intermediate product 26, in the second suspension 28 with phosphoric acid as reactant 31.

An enrichment with sulfur can expediently take place by digesting the intermediate formed as raffinate 20 with sulfuric acid as reactant 31 in the second suspension 28 , ie in the production phase carried out in the production unit 4 . In addition, by adding, for example, alkali metal or alkaline earth metal sulfates to the first and/or second suspension 6, 28, enrichment with sulfur, in particular elemental sulfur, reached. The use of ammonium sulphate, e.g. in solution, is also very well suited to increasing the sulfur content accordingly.

An enrichment of the fertilizer granules 2 with nitrogen is achieved in that the intermediate product 26 designed as a raffinate 20 is mixed with nitric acid as a reactant 31 in the production phase, preferably during the production of the second suspension 28. In addition, the first and/or second suspension 6 , 28 for enrichment with nitrogen substance, urea and/or ammonium sulfate, expediently in solution, are added. In ammonium sulphate in particular, the nitrogen is present as NH4+, which leads to improved plant availability and/or an improved supply of nitrogen to the plants. For the production of NPK fertilizer granules 2, the addition of different of the aforementioned additives 36 is necessary, expediently in particular nitric acid, urea, DCP and/or potassium salts such as potassium nitrate, potassium chloride or potassium dihydrogen phosphate. For a further improved exclusion of the intermediate product 26 formed as a raffinate 20, the reactant 31 must be offered large exchange surfaces with the intermediate product 26, so that the reaction kinetics are accelerated. This can be achieved by crushing the intermediate product 26, if necessary, using a grinder 38. The improved reaction kinetics also lead to time savings and thus to a shorter reaction time. At the same time, the risk of blockages at bottlenecks in the device 1, in particular at nozzles of a pyrolysis device 27 which is connected to the leaching device 29 and is preferably designed as a granulation device, is reduced. The grinding device 38 can be arranged in front of (upstream) and/or on the container 30 for the production of the second suspension 28 . The intermediate product 26 embodied as a raffinate 20 is comminuted in the grinding device 38 to produce the second suspension 28 so that it has an average particle diameter of preferably less than or equal to 5 mth, in particular between 50 nm and 3 mth. The grinding process preferably takes place as wet grinding of the intermediate product 26 formed as a raffinate 20, as shown in FIG. 4, for example. The advantages of wet grinding include low specific energy consumption and the processability of coarse raffinate. In addition, the agitator bearing has no contact with the second suspension 28 . Ideally, the intermediate product 26 embodied as a raffinate 20 and reactant 31 in the container 30 are well mixed with one another. For this purpose, a mixing device 39 is expediently arranged in the container 30, which is preferably designed as a blade or ribbon mixer, see in particular Fig. 2.

Expediently, mechanical energy is also supplied to the second suspension 28 to break up agglomerates, in particular by means of ultrasound. The supply of the mechanical energy serves to improve the homogenization of the second suspension 28 and thereby also to reduce the reaction time and to lower the viscosity and thus increase the flowability. The container 30 of the production unit 4 has a homogenizing device 40 for introducing mechanical energy, in particular in the form of a plate vibrator or a sonotrode. Such a homogenization device 40 arranged in the container 30 is shown, for example, in Fig.

3 shown. To carry out a continuous process, buffer tanks, not shown, are expediently designed to store the starting materials 8, the solvent 9, the intermediate product 26 and the reactant 31, but in particular the second suspension 28. In the event of partial failures, this stockpiling can help to continue operating the process continuously.

In addition, the production unit 4 can have a pH control device 41 at its disposal. This is preferably arranged in the production unit 4 upstream of the pyrolysis device 27, which is preferably designed as a granulation device. The pH value of the second suspension 28 formed from the raffinate 20 and the reactant 31 can be adjusted by controlling the pH value by means of a pH value control device 41 , as shown for example in FIG. 3 . Adjusting the pH value of the second suspension 28 affects the stickiness of the second suspension 28, which in turn is very important for the atomization of the intermediate product 26 designed as the second suspension 28 by means of the pyrolysis device 27 designed as a granulation device. The more acidic the suspension, the stickier it is. The pH value is preferably measured and the additional acid or base that adjusts the pH is metered into the container 30 that contains the second suspension 28 . The pH value is set here via the pH value control device 41. The pH value control can also be designed as an additional, external control circuit.

The device 1 for producing fertilizer granules 2 is preferably regulated and/or controlled with a control device 42 . Appropriately, for this purpose, in all inlets and outlets of the respective facilities, such as containers 5, 30, separating device 10, regeneration device 22, recirculation device 24, pyrolysis device 27, etc. Re gel valves 40 installed, which can be regulated and/or controlled by the control device 42. The aforementioned individual devices of the device 1 can all be regulated and/or controlled.

Claims

Expectations

1. A method for producing fertilizer granules (2) from a processed starting material (8) designed as a combustion residue, characterized in that a first suspension (6) is produced from the starting material (8) and a solvent (9) in a preparation phase is, whereby in the first suspension (6) in the starting material (8) ge bound pollutants (7) are at least partially dissolved out of the starting material (8) by the solvent (9), in order to then obtain a raffinate (20) the extract ( 19) at least partially separated from the first suspension (6) in order to heat an intermediate product (26) based on the raffinate (20) in the absence of air and without oxygen supply at a working pressure in a production phase that follows the processing phase, so that pyrolysis of the intermediate product (26) takes place to produce the fertilizer granules (2).

2. The method according to claim 1, characterized in that the intermediate product (26) is heated to a temperature of 150 °C to 1,500 °C, in particular to a temperature between 400 °C and 1,200 °C, during the pyrolysis.

3. The method according to claim 1 or 2, characterized in that the working pressure is formed as atmospheric air pressure plus minus 100 mbar.

4. Method according to one of the preceding claims, characterized in that in a regeneration step the extract (19) separated at least partially from the first suspension (6) is regenerated and recirculated to produce the first suspension (6).

5. The method according to claim 4, characterized in that the regeneration of the extract (19) takes place by means of ion selection and/or precipitation and/or extraction and/or evaporation/distillation and/or electrochemical purification.

6. The method according to claim 5, characterized in that the precipitation takes place as a sulfide precipitation using thiosulfate fat salts.

7. The method according to any one of the preceding claims, characterized in that the processing phase is repeated once or several times with a starting material (8) formed as a raffinate (20).

8. The method according to claim 7, characterized in that different solvents (9) are used in different processing phases.

9. The method according to any one of the preceding claims, characterized in that the first suspension (6) and / o the raffinate (20) and / or the intermediate product (26) additives are supplied tive.

10. The method according to any one of the preceding claims, characterized in that in the production phase before the pyrolysis, a second suspension (28) of raffinate (20) and Reactant (31) is prepared as an intermediate (26).

11. The method according to claim 10, characterized in that the reactant (31) is an acid or a base, the acid expediently being a mineral and/or organic acid or any mixture of these.

12. The method according to claim 11, characterized in that the organic acid is a short-chain carboxylic acid having a number of up to six carbon atoms.

13. The method according to claim 11 or 12, characterized in that the organic acid has a carbon-oxygen ratio of 1:1 or 1:2.

14. The method as claimed in one of the preceding claims, characterized in that the starting material (8) is ground in a grinding step before and/or the first suspension (6) during the preparation phase.

15. Method according to one of the preceding claims, characterized in that the intermediate product (26) based on the raffinate (20) is ground in a grinding step before and/or during the production phase.

16. The method according to any one of the preceding claims, characterized in that the reactant (31) at the beginning of the second suspension (28) has a temperature of 10 °C to 40 °C.

17. The method according to any one of the preceding claims, characterized in that the reactant (31) is placed and this on the raffinate (20) based intermediate product (26) is added.

18. The method according to any one of the preceding claims, characterized in that the first suspension (6) has an extraction time of in particular up to 90 minutes and / or the second suspension (28) has a reaction time of up to 90 minutes.

19. The method according to any one of the preceding claims, characterized in that a temperature of the second suspension (28) between 20 ° C and 80 ° C prevails during the reaction time.

20. The method according to any one of the preceding claims, characterized in that the first suspension (6) and/or the intermediate product (26) is supplied with mechanical energy for breaking up agglomerates, in particular by means of ultrasound.

21. The method according to any one of the preceding claims, characterized in that the intermediate product (26) formed as the second suspension (28) is granulated by means of spray granulation or spray agglomeration.

22. The method according to any one of the preceding claims, that the process for the production of fertilizer granules (2) is a continuous process.

23. Device (1) for the production of fertilizer granules (2) from a processed out as a combustion residue formed starting material (8), characterized in that the Device (1) has a processing unit (3) with an ex traction stage (11), which has a container (5) for preparing a first suspension (6) from the starting material (8) and a solvent (9), and with a Separating device (10) for at least partially separating the extract (19) from the first suspension (6) to obtain a raffinate (20) and that the device (1) also has a production unit (4) which has a pyrolysis device ( 27) for producing the fertilizer granules (2) from an intermediate product (26) based on the raffinate (20).

24. Device (1) according to claim 23, characterized in that the production unit (4) has a leaching device (29), the leaching device (29) having a container (30) for producing a second suspension (28) from the raffinate ( 20) and the reactant (31).

25. Device (1) according to claim 24, characterized in that the container (5) for producing the first suspension (6) and the container (30) for producing the second suspension (28) as separate containers (5, 30 ) are trained.

26. Device (1) according to claim 24, characterized in that the container (5) for producing the first suspension (6) and the container (30) for producing the second suspension (28) as one container (5, 30) are trained.

27. Device (1) according to one of claims 23 to 26, characterized in that the pyrolysis device (27) is designed as a granulation device in the form of a fluidization apparatus, in particular as a high-temperature fluidized bed apparatus or high-temperature spouted bed apparatus.

28. Device (1) according to one of claims 23 to 27, characterized in that the processing unit (3) has several containers (5) for producing a suspension (6) and one or more separating devices (10) for at least partially separating the Extract (19) from the corresponding suspension (6), wherein the plurality of containers (5) is assigned a separating device (10) or each container (5) has a separate separating device (10).

29. Device (1) according to one of claims 23 to 28, characterized in that the processing unit (3) has one or more regeneration devices (22) for the extract (19).

30. Device (1) according to claim 29, characterized in that the processing unit (3) has one or more recirculation devices (24) for the regenerated solvent (9).

31. Device (1) according to one of claims 23 to 30, characterized in that the production unit (4) has a pH control device (41).

32. Device (1) according to one of claims 23 to 31, characterized in that the leaching device (29), in particular the container (30) for producing the second suspension (28), is designed as a tubular reactor (35).